Method of influencing the gradation of color-photographic printing material



June 1, 1965 H. BERGER El'AL 3,186,841

METHOD OF INFLUENCING THE GRADATION OF COLOR-PHOTOGRAPHIC PRINTING MATERIAL Filed Aug. 29, 1960 INVENTORS. HE lNZ BERGER, HANfiYBEPGHAUS.

1755i ATTORNEY) United States Patent "ice 3,185,841 WTHOD OF HJFL hNtClNG I'll-E GRADATION OF COLOR-PHOTOGRAPHIQ PRENTEIG MATERIAL Heinz Berger, Leverlrusen, and Hans Berghans, (Iologne- Deutz, Germany, assiguors to Agra Ahtiengesellschaft, lleverhusen, Germany, a corporation of Germany Filed Aug. 29, 1960, Ser. No. 52,384- (Ilaims priority, application Germany, dept. 3, 1959, A 323% 2 Claims. (Ci. 96-23) The present invention relates to a method of modifying the gradation of color-photographic material by an additional non-imagewise exposure.

It is known to produce an increase in sensitivity by causing a latent eifect on photographic materials, both of black-and-white and color layers, by means of supplementary exposure. Neither an appreciable loss in contrast nor a color displacement occur when increasing the sensitivity of color materials.

It has now been found that the gradation is influenced when printing from subtractive multi-color originals on to subtractive multi-laycr material by a general supplementary exposure prior to, during, or after the printing exposure. In this connection, depending on the material being used, advantageously a flattening of the high-lights is achieved when printing from a negative on to a positive material, and preferably a flattening of the shadows is achieved when printing from a reversal diapositive on to a reversal printing material.

The procedure adopted in practice is that the supplementary exposure is not carried out with unfiltered light, but with a filtering which corresponds to the basic number or the neutral value of the printing material, while the actual printing exposure is carried out with the filtering which is necessary for the neutral position of the image. In accordance therewith, the filtering of the supplementary exposure can be different from the filtering of the image exposure.

Basic numbers and neutral values are recognized terms of art and are discussed in such standard texts as Agfacolor, by Heinz Berger, second edition, copyright 1955 by W. Girardet, Wuppertal-Elberfeld, Germany. Reference is particularly made to pages l50l54 of this text.

On the basis of the known methods of increasing the sensitivity by producing a latent effect, it was not to be foreseen that a general supplementary exposure would cause a deflection in gradation in a color photographic printing material. However, if such a supplementary exposure is carried out in addition to the printing exposure proper with white, unfiltered light in the copying apparatus, a color change between light and shadow of the final image is produced in most cases. The reason for this is that a color photographic printing material as produced is in most cases not neutral for the printing li ht source being used. In order to make the printing material neutral, thi must in fact be so colored by using colored filters that, for example, a silver grey wedge or a black-and-white negative is printed grey or is reproduced in substantially neutral form on to the printing material. Consequently, the filtering necessary here is also generally designated as basic number or neutral value. On the other hand, it would be incorrect to carry out the general supplementary exposure with the use of the filtering which must be used for the neutral print from a color negative, for in this case not only the basic color shade of the printing material (neutral value), but simultaneously also the color shade of the negative, are balanced.

With the process according to the invention, the following procedure is adopted:

First of all, the neutral value of the color photographic printing material in the printing apparatus being used 3,186,841 Fatented June 1, 1965 is established, it being advantageous to use a printing material with very hard gradation. Then, a general supplementary exposure without printing original, using neutral filtering, is carried out prior to, during or after the image exposure proper, depending on the existing printing original or the desired final image gradation, the intensity or the duration of the supplementary exposure being chosen in accordance with that which, from experience, is necessary for the desired flattening of the gradation of the image. The print filtering is separately established in known manner for the actual main exposure through the printing original.

According to one particular form of application of the process, it is possible to bring a per se unstable printing material into color balance, or vice versa. For this purpose, the layers must be initially exposed with too steep gradations, using the light to which they are sensi tive. If for example a so-called unstable gradation of the printing material exists, that is to say, if the three color density curves of the color photographic multi-layer material are not parallel or superimposed or at least one gradation is steeper than the others, a neutral position of the material can be produced by initially exposing the emulsion layer with the steeper gradation with the light to which it is sensitive, whereby the desired flattening of this individual gradation is obtained.

The supplementary exposure can if necessary be carried out with subtractive or additive filters.

he process is mainly suitable for the machine processing of color photographic multi-layer material, but it can also be used for influencing the gradation of sheet material.

A bending in gradation of a single layer of a multilayer material, as produced by the process of the invention, is illustrated by way of example in the accompanying figure.

Curve I shows the gradation curve which was obtained Without prior exposure. v

For curve ll, an initial exposure amounting to 4.3 percent of the total exposure was employed.

For curve Ill, the initial exposure is 7 percent of the total exposure.

Example A multi-layer positive material of the following composition is used:

On a paper support coated with a baryta-layer was first applied a silver chloride gelatine emulsion sensitized to red light by a dye of the formula on orr=o-s u 1 1 I 0: o-on= o W a lgHg and containing the following color coupler compound I NH u siS 03H The middle layer consists of a silver chloride gelatine emulsion sensitized to green light by a dye of the formula and incorporated therein a color coupler compound of the following formula H CC-- 11Has It COOH For the front layer was used a non-sensitized silver bromide gelatine emulsion which is sensitive to blue light. Said layer contains a color coupler of the formula First the neutral value of the above-described positive material is established by the following operation:

A number of subtractive color filters is combined. Through this filter combination a black-white transparency is printed on the above-mentioned positive material using white light. The filter combination is varied so long till the black-white transparency is reproduced on the positive material as a neutral grey image without any color-shade. If, for example, a blue color-shade appears, a magenta and a cyan filter of adequate density have to be used for getting a neutral grey reproduction. The ascertained filter combinations are used later on for the supplementary exposure.

An exposed 3-layer negative film is printed on the above-mentioned positive material by using a subtractive filter combination ina manner Well-known, so that the original image of the negative film is reproduced on the printing material without color-defects. If, for example, the color-negative has a green color-shade, a magenta color filter of adequate density has to be used for this main or image exposure.

Afterwards the printing material is exposed without interposition of the original using diffused light. The filtering thereof corresponds to the neutral value of the printing material. The intensity, respectively the time of exposure should be -20 percent of the main or image exposure.

The positive material is developed, bleached, fixed and Washed in the manner well-known in color photography.

There is obtained a neutral print of the original with a -value of only 2.4. The 'y-value of the same print working without supplementary exposure is 3.0.

It makes no difference if the supplementary exposure is applied prior to or during the image exposure.

The principle of the method of the invention is not limited to subtractive multi-color processes. Application in connection with an additive multi-color process is possible without difficulties.

What is claimed is:

1. A process for influencing the gradation of a color photographic printing material when copying from a multicolor negative of an original image onto a multilayer positive printing material containing at least three silver halide emulsion layers, each layer of which is sensitive to one of the different regions of the visible spectrum of the group consisting of red, green and blue, and each layer of which contains a difierent color coupler that is capable of reacting with the oxidation product of an aromatic primary amine developer to form a dye, the color coupler in the green-sensitive layer to form a magenta dye, the color coupler in the red-sensitive layer to form a cyan dye, and the color coupler in the bluesensitive layer to form a yellow dye, which process comprises (a) providin said multilayer positive printing material in which the emulsions have balanced contrasts,

(b) determining the characteristics of a filter which when interposed in a beam of white light that is projected on the printing material through a blackand-white transparency causes that transparency to be reproduced on the positive material as a neutral gray image without any distinct color hue,

(c) exposing said printing material to the multicolor negative through a combination of subtractive color filters to obtain light having a color composition which causes said printing material to produce a positive print of the multicolor negative in the colors of the original image,

(d) subjecting the said positive printing material to a supplementary exposure from a beam of white light projected through the filter of step (1)), this supplementary exposure having an intensity between 10 and 20 percent of the image exposure (c), and

(e) subsequently developing, bleaching, fixing, and washing the thus exposed positive printing material.

2. The process of claim 1 in which the printing material has a very hard gradation.

References Cited by the Examiner UNITED STATES PATENTS 2,285,262 6/42 Fess et al 96-23 X 2,352,914 4/44- Rackett 96-23 2,529,975 11/50 Smith 9623 2,780,155 2/57 Debrie 9623 X FOREIGN PATENTS 1,007,622 5/57 Germany.

OTHER REFERENCES Frost: German printed application, A2l3281X/ 57a, Aug. 9, 1956.

Berger: Agfacolor, second edition, page -154, W. Girardet, Wuppertal-Elberfeld, Germany (1955).

Gordon: British Journal of Photography, vol. 102, pages 440-1 (1955).

NORMAN G. TORCHIN, Primary Examiner.

PHILIP E. MANGAN, HAROLD H. BURSTEIN,

. Examiners. 

1. A PROCESS FOR INFLUENCING THE GRADATION OF A COLOR PHOTOGRAPHIC PRINTING MATERIAL WHEN COPYING FROM A MULTICOLOR NEGATIVE OF AN ORIGINAL IMAGE ONTO A MULTILAYER POSITIVE PRINTING MATERIAL CONTAINING AT LEAST THREE SILVER HALIDE EMULSION LAYERS, EACH LAYER OF WHICH IS SENSITIVE TO ONE OF THE DIFFERENT REGIONS OF THE VISIBLE SPECTRUM OF THE GROUP CONSISTING OF RE, GREEN AND BLUE, AND EACH LAYER OF WHICH CONTAINS A DIFFERENT COLOR COUPLER THAT IS CAPABLE OF REACTING WITH THE OXIDATION PRODUCT OF AN AROMATIC PRIMARY AMINE DEVELOPER TO FORM A DYE, THE COLOR COUPLER IN THE GREEN-SENSITIVE LAYER TO FORM A MAGENTA DYE, THE COLOR COUPLER IN THE RED-SENSITIVE LAYER TO FORM A CYAN DYE, AND THE COLOR COUPLER IN THE BLUESENSITIVE LAYER TO FORM A YELLOW DYE, WHICH PROCESS COMPRISES (A) PROVIDING SAID MULTILAYER POSITIVE PRINTING MATERIAL IN WHICH THE EMULSIONS HAVE BALANCED CONTRASTS, (B) DETERMINING THE CHARACTERISTICS OF A FILTER WHICH WHEN INTERPOSED IN A BEAM OF WHITE LIGHT THAT IS PROJECTED ON THE PRINTING MATERIAL THROUGH A BLACKAND-WHITE TRANSPARENCY CAUSES THAT TRANSPARENCY TO BE REPRODUCED ON THE POSITIVE MATERIAL AS A NEUTRAL GRAY IMAGE WITHOUT ANY DISTINCT COLOR HUE, (C) EXPOSING SAID PRINTING MATERIAL TO THE MULTICOLOR NEGATIVE THROUGH A COMBINATION OF SUBTRACTIVE COLOR FILTERS TO OBTAIN LIGHT HAVING A COLOR COMPOSITION WHICH CAUSES SAID PRINTING MATERIAL TO PRODUCE A POSITIVE PRINT OF THE MULTICOLOR NEGATIVE IN THE COLORS OF THE ORIGINAL IMAGE, (D) SUBJECTING THE SAID POSITIVE PRINTING MATERIAL TO A SUPPLEMENTARY EXPOSURE FROM A BEAM OF WHITE LIGHT PROJECTED THROUGH THE FILTER OF STEP (B), THIS SUPPLEMENTARY EXPOSURE HAVING AN INTENSITY BETWEEN 10 AND 20 PERCENT OF THE IMAGE EXPOSURE (C), AND (E) SUBSEQUENTLY DEVELOPING, BLEACHING, FIXING, AND WASHING THE THUS EXPOSED POSITIVE PRINTING MATERIAL. 